1. Field of the Invention
The present invention relates to a displacement type fluid, machine such as a pump, a compressor or expander.
2. Description of the Prior
The gyration type displacement type fluid machine of this kind (as will be abbreviated to the xe2x80x9cgyration type fluid machinexe2x80x9d) has been proposed in Unexamined Japanese Patent Publication No. 55-23353 (Publication ), U.S. Pat. No. 2,112,890 (Publication 2), Unexamined Japanese Patent Publication No. 5-202869 (Publication 3) and Unexamined Japanese Patent Publication No. 6-280758 (Publication 4).
The gyration type fluid machine, as disclosed in any of Publications 1 to 4, has essentially advantageous features as the displacement type fluid machine in that it has multiple cylinders and a completely balanced rotating shaft so that it can be lowered in pressure pulsations and vibrations and in the relative sliding rate between a displacer and a cylinder thereby to reduce the frictional loss.
However, the stroke of the individual working chambers to be formed by a plurality of vanes composing a displacer and a cylinder from the suction completion to the discharge completion is as short (e.g., about one half of the rotary type and equal to that of the reciprocating type) as about 180 degrees in terms of a shaft rotation angle xcex8 so that the flow velocity in the discharge process is so high as to increase the over compression loss thereby to cause a problem of the reduction in the performance. In the fluid machine of this type, on the other hand, a rotating moment to rotate the displacer itself acts as a reaction from the compressed working fluid upon the displacer so that the moment is received by the contact between the cylinder and the displacer. In the structure disclosed in any of Publications 1 to 4, however, the working chambers from the suction completion to the discharge completion are concentrated on one side of the drive shaft. As a result, the rotating moment to act on the displacer grows excessive to invite a defect that the performance and reliability are troubled by the wear of the vanes. Unexamined Japanese Patent Publication No. 9-268987 (Publication 5) has proposed a displacement type fluid machine as a gyration type fluid machine having solve that defect.
Now, in order to achieve a high efficiency in a displacement type fluid machine in which one space is formed by the inner wall face of a cylinder and the outer wall face of a displacer when the center of the displacer is located at the center of rotation of a rotating shaft, and in which a plurality of spaces are formed when a positional relationship between the displacer and the cylinder is located at the position of gyration, it is necessary to lower the fluid friction loss and the mechanical friction loss and to minimize the internal leakage of the working fluid which will occur through the gap (i.e., the radial gap) of the sliding portion between the displacer and the cylinder forming the working spaces (or working chambers).
In the contour of the prior art in which the cylinder and the displacer are so contoured that a gap of a predetermined width (or a gyration radius) is formed between the cylinder and the displacer when they are made concentric, however, the radial gap is enlarged by the clearance of the shaft drive system for moving the displacer and by the rotating moment acting upon the displacer to increase the internal leakage of the working fluid thereby to cause a problem that the machine performance is lowered.
When the eccentricity of the drive shaft is increased to enlarge the gyrating radius of the displacer so as to reduce that radial gap, on the other hand, the displacer contacts at the outer peripheral portion of its contour with the cylinder so that a seriously excessive load (or the reaction of the contact portion) acts upon the drive shaft because of the small contact angle to raise a problem of the reduction in the reliability such as the seizure of the shaft.
An object of the invention is to provide a displacement type fluid machine in which one space is formed by the inner wall face of a cylinder and the outer wall face of a displacer when the center of the displacer is located at the center of rotation of a rotating shaft, and in which a plurality of spaces are formed when a positional relationship between the displacer and the cylinder is located at the position of gyration, wherein the load on the drive shaft is lighted while reducing the internal leakage of the working fluid.
The above-specified object is achieved by providing a displacement type fluid machine in which one space is formed by the inner wall face of a cylinder and the outer wall face of a displacer when the center of said displacer is located at the center of rotation of a rotating shaft, and in which a plurality of spaces are formed when a positional relationship between said displacer and said cylinder is located at the position of gyration, wherein when the center of said displacer is located at the center of rotation of said rotating shaft, the gap between the inner wall face of said cylinder and the outer wall face of said displacer is different depending upon the position.
On the other hand, the aforementioned object is achieved by providing a displacement type fluid machine in which one space is formed by the inner wall face of a cylinder and the outer wall face of a displacer when the center of said displacer is located at the center of rotation of a rotating shaft, and in which a plurality of spaces are formed when a positional relationship between said displacer and said cylinder is located at the position of gyration, wherein when the center of said displacer is located at the center of rotation of said rotating shaft, the gap between the inner wall face of said cylinder and the outer wall face of said displacer is made alternately wide and narrow.
On the other hand, the aforementioned object is achieved by providing a displacement type fluid machine in which one space is formed by the inner wall face of a cylinder and the outer wall face of a displacer when the center of said displacer is located at the center of rotation of a rotating shaft, and in which a plurality of spaces are formed when a positional relationship between said displacer and said cylinder is located at the position of gyration, wherein when the center of said displacer is located at the center of rotation of said rotating shaft, the gap between the inner wall face of said cylinder and the outer wall face of said displacer is made narrow at the portion having a large curvature of the outer wall curve of said displacer.
Moreover, the aforementioned object is achieved by providing a displacement type fluid machine in which a displacer and a cylinder are arranged between end plates, in which one space is formed by the inner wall face of said cylinder and the outer wall face of said displacer when the center of said displacer is located at the center of rotation of a rotating shaft, and in which a plurality of spaces are formed when a positional relationship between said displacer and said cylinder is located at the position of gyration, wherein said displacer is caused by a rotating moment in a fixed direction to slide into contact with said cylinder in a predetermined section, and wherein said cylinder and said displacer are so contoured that the distance in the sliding contact section between the inner wall face of said cylinder and the outer wall face of said displacer is smaller than that of the remaining sections when the center of said displacer is located at the center of rotation of a rotating shaft.
As a result, the play of the displacer itself in the rotational direction with the cylinder and the displacer meshing with each other is reduced to solve the problem that the radial gap is enlarged by the clearance of the shaft drive system and by the rotating moment acting upon the displacer. At the same time, no contact prevails except the sliding contact section receiving the rotating moment acting upon the displacer, thereby to eliminate the problem that the reliability is lowered by the excessive load acting upon the drive shaft. Thus, it is possible to provide a gyration type fluid machine which can hold the radial clearance between the cylinder and the displacer optimum and can improve the performance and the reliability.